Vacuum suction machine with high efficiency filter and operating interlock

ABSTRACT

A vacuum motor and fan are mounted within a housing, the lower end of which receives a high efficiency particle filter. The bottom of the housing includes a series of projections adapted to be received in corresponding apertures on an upper flange of the filter to prevent replacing the filter with an improper one. The projection/apertures also promote proper seating of the seal between the filter canister and the housing. A separate projection on the filter engages and actuates a lock-out switch carried by the housing to permit the machine to operate only when the filter is of proper size and capacity and it is properly seated on the housing.

FIELD OF THE INVENTION

The present invention relates to vacuum suction machines having a highefficiency particulate air filter which are designed for the saferemoval of hazardous materials, such as those containing asbestos or thelike.

BACKGROUND OF THE INVENTION

Vacuum suction machines have come into widespread use for the removal ofhazardous materials. Such machines typically employ a number of filterstages. The initial filters are used to remove debris and particles oflarger size, and a final stage usually consists of a special filterknown in the art as a high efficiency particulate air or HEPA filter.HEPA filters are especially designed to remove particles from airpassing through the filter where the particle size extends down tomicroscopic levels.

HEPA filters, like other filters, become clogged with use and have to bereplaced periodically. It is important that a replacement HEPA filterhave the same capacity and specifications as the original HEPA filterbecause when a HEPA filter is replaced, it is enclosed within themachine and cannot ordinarily be seen by the operator. And an operatormay not always take the precaution of opening the machine to make surethat the HEPA filter being used is a proper one.

It is also possible that some operators who are particularly carelessmay remove the HEPA filter and use the vacuum suction machine for other,more conventional uses. When the operator replaces the machine afterconventional use, a careless operator may fail to put the HEPA filterback in the machine or to note on the machine that it is not equippedwith a HEPA filter. Subsequent operation of such a machine without aHEPA filter for removal of hazardous material would obviously present ahazard to a subsequent operator.

It is also important that HEPA filters be designed for proper sealingwith the housing for the vacuum motor because there is a substantialpressure drop across the filter and if there is any leakage ofcontaminated air around, rather than through the filter, such acondition could also present a hazard to the environment and tooperators.

SUMMARY OF THE INVENTION

The present invention overcomes the above problems by providing anactuating member attached to the canister of the HEPA filter whichcooperates with and is received in the motor housing. A position switchis mounted to the housing and senses the actuating member on the filterwhen the filter is properly assembled to the motor housing. The positionswitch is connected in circuit with the motor and operating switch sothat when the HEPA filter is properly in place the motor is enabled tooperate, and when the HEPA filter is removed, the motor is disabled.

The canister on the HEPA filter includes an upper mounting flange whichis provided with two series or apertures. One set of apertures is usedto mount the filter to the motor housing, and the other set of aperturesis located to receive a corresponding set of projections integral withthe motor housing. Thus, when the filter is assembled to the housing,the filter is properly located so that the mounting flange engages thehousing in the proper location and angular disposition. Theseprojections and apertures further prevent replacement of the originalHEPA filter with another filter which may not meet the specifications ofthe machine. If a replacement filter does not have the proper capacityor removal specifications. It may fail to meet government specificationsor it may present a hazard during operation.

The projections and apertures also insure proper seating of the filteron the motor housing to effect a seal between the two. Atongue-in-groove seal is formed between the motor housing and the filtercanister. The effectiveness of the seal is insured when the filter isproperly located and assembled to the filter housing.

Other features and advantages of the present invention will be apparentto persons skilled in the an from the following detailed description ofa preferred embodiment accompanied by the attached drawing whereinidentical reference numerals will refer to like parts in the variousviews.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a vertical cross-sectional view of a vacuum suction machineincorporating the present invention;

FIG. 2 is an enlarged vertical cross section of the filter and the lowerportion of the motor housing in assembled relation; and

FIG. 3 is a perspective view showing the motor housing and HEPA filterprior to assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Turning first to FIG. 1, there is shown a five-stage vacuum suctionmachine generally designated 10 including a container or canister 11, inthe general form of a cylinder or drum. The container 11 forms areceptacle for collecting debris and it has an open top on which ismounted a vacuum motor housing generally designated 12. In the side wallof the container 11, toward the bottom, there is an intake assembly 13to which a hose coupled to a removal tool would ordinarily be attached.An tubular extension 15 is attached to the inner part of the intake 13,and it extends within the lower portion of the container 11. A paper bagis mounted to the extension 15 for collecting larger debris; and the bag16 acts as a first or course filter, as well as a disposable refuse bag.

A second paper bag 18 and a cloth filter bag 19 are located within thecontainer 11, and they act as the second and third filter stagesrespectively. The upper perimeter of the outer paper bag 18 is foldedover the upper edge of the container 11, and the upper perimeter of thecloth bag 19 is secured to a mounting ring 20 to which an inner wireframe or basket 21 is mounted. The frame 21 prevents the bags 18, 19from collapsing onto the HEPA filter, as described below.

The motor housing 12 includes an upper section or dome 23 and a lowersection or base 24 which includes an integral bottom 225. The centralportion of the bottom of the motor housing is in the form of a grill orgrid 25A (FIG. 3) so that air can readily pass through it, as will beappreciated by those skilled in the art.

Housed within the upper portion 23 of the motor housing is an electricmotor generally designated 27 which is connected to and drives a vacuumblower generally designated 28. The motor and blower are mounted to aplate 29; and the upper section 23, lower section 24 and motor mountingplate 29 are all secured together by fasteners 30. Below the vacuumblower 28 there is an adapter plate 32A which is sealed to the blowerintake and partially defines the upper portion of a vacuum chambergenerally designated 34. Chamber 34 is in communication with thedischarge of a high efficiency particulate air (HEPA) filter generallydesignated 35 via grid 25A formed in the bottom of the motor housing, asseen best in FIG. 2. An impact filter assembly generally designated 36is mounted to the bottom of the HEPA filter 35.

A cover 36A provided with a handle 37A is conventionally mounted to thetop of the upper section 23 of the motor housing by means of fastenersfitted through spacers 38A. The cover 36A has a side skirt 39A, thelower portion of which is spaced above the upper section 23 of the motorhousing to define a peripheral aperture 40A through which air is drawnto cool the motor. The cooling air is exhausted outwardly through 20openings between upper section 23 and the motor mounting plate 29.

Air carrying debris passes through the five filter stages describedabove, the chamber 34 and the vacuum blower 28, from which the air isexhausted radially outward at 28A. The clean air is then exhaustedoutwardly between the motor mounting plate 29 and the lower housingsection 24. What has been described thus far is generally representativeof vacuum suction machines used for removal of hazardous material whichhave been commercially available prior to the instant invention.

Turning now to FIGS. 2 and 3, the HEPA filter 35 includes a generallycylindrical side wall 37, an upper mounting flange 38, an upperperipheral projection ring 39 and a lower flange 40. A conventionalfilter labyrinth of paper generally designated 42 forms the actualfiltering material of the HEPA filter.

The pre-filter or fourth-stage filter (or "impact" filter, as it issometimes referred) 36 includes a mounting ring 44 which snaps onto themounting flange 40 at the base of the canister 37 of the HEPA filter,and which includes a lower grid 45, and an upper filter retainer 47.Between the lower grid 45 and the upper retainer grid 45 47, there is alayer of filter material 48. The centers of the upper and lower grids45, 46 may be pinned together by a fastener/spacer 49, as illustrated.

Turning now to the HEPA filter as seen in FIG. 2, it includes a lowergrid 50 immediately above the impact filter 36 and below the particulatefilter medium 42, which conventionally consists of a labyrinth of paperand spacers. The upper ring 39 includes upwardly extending projectionsor fingers 52, 53 respectively, which are located at diagonally oppositepositions on the ring 39. The ring 39 is attached, as by chemicalbonding or heat or sonic welding to the inner surface of the side wall37. From FIG. 2, it will be seen that the bottom wall 25 of the lowersection 24 of the motor housing is provided with first and secondapertures 54, 55 for receiving the fingers 52, 53 respectively.Similarly, the adapter plate 32 is provided with an aperture 57 forreceiving the plunger or actuator of an electrical position switch $8(sometimes referred to as the lockout switch) mounted to a flange 59.The location of the aperture 57 is such that when the HEPA filter isproperly seated, one of the actuating fingers, 52, 53 engages theplunger of the switch 58 to actuate it.

The switch 58 is connected in circuit with the power lead from the mainon/off switch mounted on the motor housing. The switch 58 is a normallyopen switch so that when the HEPA filter is removed, the switch 58 isopened and disables or "locks out" the motor by opening a power line tothe motor. When the HEPA filter is properly assembled to the motorhousing, however, one of the actuating fingers or members 52, 53actuates the switch 58 and enables the motor to operate normally. TheHEPA filter is secured to the bottom wall 25 of the lower section of themotor housing by threaded fasteners 61 which are received throughapertures 62 in the mounting flange 38. As best seen in FIG. 3, thereare eight such apertures 62 on the mounting flange 38 of the HEPA filterfor receiving fasteners.

There are four additional apertures designated 65 in FIG. 3 and locatedat predetermined locations which register with projections or pinsextending from the bottom plate 25 of the motor housing. The pins 66 onthe motor housing and apertures 65 on the HEPA filter must register andmesh before the filter can be assembled and fastened to the housing.This insures that filters of improper size or capacity will not be usedin the machine. This combination of pins and apertures also helps locatethe filter in angular orientation so that the actuating members 52, 53are in proper register with the apertures 54, 55 of the bottom plateduring assembly. This combination further insures proper seating of atongue-in-groove seal 68 between the bottom wall of the motor housingand the upper mounting flange 38 of the HEPA filter.

In the illustrated embodiment, an annular groove of wedge-shaped crosssection 69 is formed in the flange 38 facing upwardly, to receive acorrespondingly shaped annular tongue 71 formed on the bottom of themotor housing 25 (See FIGS. 2 and 3). Conversely, the tongue 71 could beformed on the HEPA filter and the groove could be formed in the bottomsurface of the motor housing. Both the tongue and the groove extendaround the periphery of the filter and form a desirable labyrinth sealbetween the motor housing and the HEPA filter when the HEPA filter isproperly assembled and fastened to the motor housing to insure that airdoes not pass around the filter but, rather, is forced to pass throughthe filter in operation.

It will thus be apparent to persons skilled in the art that thearrangement of projections and apertures is a first measure against theuse of improper filters and they further insure proper assembly and sealengagement. It will also be appreciated that a complete peripheral sealin the form of a tongue-in-groove arrangement provides a labyrinth sealand desirably insures a continuous seal between the motor housing andthe HEPA filter. Finally, the finger/actuators 52, 53 also serve tolocate the filter relative to the motor housing and to insure againstimproper filter replacement, but they also preclude operation of themachine without the presence of a HEPA filter.

Having thus disclosed in detail a preferred embodiment of the invention,persons skilled in the art will be able to modify certain of thestructure which has been illustrated and to substitute equivalentelements for those disclosed while continuing to practice the principleof the invention; and it is, therefore, intended that all suchmodifications and substitutions be covered as they are embraced withinthe spirit and scope of the appended claims.

We claim:
 1. In a vacuum machine for collecting hazardous materials, thecombination comprising: a motor housing having an air discharge openingand an air inlet opening: a motor and a vacuum fan mounted within saidhousing for generating a vacuum in a portion of said housing in fluidcommunication with said air inlet opening: a container providing areservoir for collecting material and including an air intake; means formounting said motor housing to said container; a high efficiencyparticle filter having a canister with a generally cylindrical sidewall; said filter being mounted to the bottom of said motor housing andcovering said inlet opening, said filter including at least oneactuating member; a switch connected in circuit with said vacuum motorand mounted to said housing such that when said filter isproperly/assembled to said housing said actuating member of said filterengages and actuates said switch to permit said motor to be energized;said canister including an upper circular mounting flange and said motorhoming including a bottom wall receiving said mounting flange of saidfilter, one of said mounting flange and bottom wall defining a circularperipheral groove and the other defining a circular peripheral tongue insaid groove and .[.seal.]. .Iadd.sealed .Iaddend.therewith. said filterbeing assembled to said motor housing; means for releasably securingsaid mounting flange to the bottom motor housing; and wherein one ofsaid mounting flange and bottom wall defines a plurality of projectionsand the other defines a plurality of apertures in register with andreceiving said projections such that said filter is properly assembledto said housing, thereby to preclude improper assembly of a filter tosaid housing. .Iadd.
 2. An improved high efficiency particle filter foruse in a vacuum machine for collecting hazardous materials having amotor housing with an air discharge opening and an air inlet opening, amotor and a vacuum fan mounted within said housing for generating avacuum, and a portion of said housing being in fluid communication withsaid air inlet opening, a container providing a reservoir for collectingmaterial and including an air intake, said motor housing being mountedin said container, a switch connected in circuit with said vacuum motorand mounted to said motor housing and permitting said motor to beenergized when said switch is actuated, said motor housing including abottom wall defining said air inlet opening and including a circularperipheral sealing tongue extending about said air inlet opening on thebottom surface thereof and further including a plurality of locatingapertures spaced at predetermined locations about said air inlet openingof said motor housing, said filter comprising: a canister having agenerally cylindrical side wall and including an upper circular mountingflange adapted to be mounted to the bottom wall of said motor housingand covering said inlet opening, said filter including at least oneactuating member adapted to engage said switch to enable said vacuummotor to be energized when said filter is properly assembled to saidhousing, said upper circular mounting flange of said filter furtherincluding circular means adapted to engage said sealing tongue of saidmotor housing to seal therewith when said filter is mounted to saidbottom wall of said motor housing under compression of the mountingmeans, said mounting flange of said filter further defining a pluralityof projections located to be received in said locating apertures of saidbottom wall of said housing to register therewith and be receivedtherein when said filter is assembled to said housing. .Iaddend..Iadd.3. The apparatus of claim 2 wherein said sealing means located insaid mounting flange of said filter comprises a peripheral grooveadapted to receive and seal with said peripheral tongue of said bottomwall of said housing. .Iaddend.